1. Field of the Invention
The present invention relates to high frequency electromagnetic circuits and systems. More specifically, the present invention relates to waveguide power dividers for use with radar systems.
2. Description of the Related Art
High frequency (e.g. microwave) circuits and systems typically require a division of power between two or more paths. Radar duplexers, for example, require an equal division of input power among the four output arms while simultaneously minimizing the phase difference between any two arms and the amount of reflected power. A duplexer is a device that splits microwave (radar) energy between two or more paths.
Conventional four-way power dividers that operate between 1 and 140 GHz are typically constructed from three two-way power dividers. Two-way power dividers automatically provide equal power division via symmetry and typically use a single inductive septum or post to match the input impedance.
To ensure equal division of power and high return losses in a four-way power divider constructed from three two-way power dividers, however, one must allow enough distance between adjacent two-way power dividers to allow evanescent waveguide modes to die out. The disadvantage of such structures is therefore size. Even if such a power divider is constructed as a single unitxe2x80x94rather than by connecting together three separate two-way dividersxe2x80x94it must be large to achieve equal power division and high return losses.
Hence, a need exists in the art for a compact four-way power divider for high frequency (microwave) applications.
The need in the art is addressed by the compact four-way waveguide power divider of the present invention. The inventive power divider includes an input waveguide that terminates at a junction with two adjacent waveguides on opposite sides of the input waveguide. On the opposite side of the junction is a conducting wall into which is built an inductive septum. The inductive septum serves to partially match the input impedance of the structure. Second and third inductive septums are also built into the output arms of the power divider. The purpose of the second and third septums is twofold. In addition to partially matching the power divider""s input impedance, the positions of the second and third septums can be adjusted to equalize the power division between the output arms. Hence, the waves exiting the four output arms of the power divider have highly equalized amplitudes and phases. Further, the phases at the output ports are equalized by adjusting the lengths of the output arms.
A novel feature of the invention is the use of offset inductive septums in the output arms to achieve equalized power division. This allows the input and output waveguides to be placed in very close proximity, resulting in an extremely compact structure. The total width of the compact four-way power divider is the sum of the widths of the input and two output waveguides (each output waveguide containing two output arms) plus the thickness of the waveguide walls.